Alloreactive CD4+ T cells play a central role in allograft rejection. However, the post-transcriptional regulation of the effector program in alloreactive CD4+ T cells remains unclear. N6-methyladenosine (m6A) RNA modification is involved in various physiological and pathological processes. Herein, we investigated whether m6A methylation plays a role in the allogeneic T-cell effector program. m6A levels of CD4+ T cells from spleens, draining lymph nodes and skin allografts were determined in a skin transplantation model. The effects of a METTL3 inhibitor (STM2457) on CD4+ T-cell characteristics including proliferation, cell cycle, cell apoptosis and effector differentiation were determined after stimulation of polyclonal and alloantigen-specific (TEa; CD4+ T cells specific for I-Eα52-68) CD4+ T cells with α-CD3/α-CD28 monoclonal antibodies and cognate CB6F1 alloantigen, respectively. We found that graft-infiltrating CD4+ T cells expressed high m6A levels. Administration of STM2457 reduced m6A levels, inhibited T-cell proliferation and suppressed effector differentiation of polyclonal CD4+ T cells. Alloreactive TEa cells challenged with 40 μm STM2457 exhibited deficits in T-cell proliferation and T helper type 1 cell differentiation, a cell cycle arrest in the G0 phase and elevated cell apoptosis. Moreover, these impaired T-cell responses were associated with the diminished expression levels of transcription factors Ki-67, c-Myc and T-bet. Therefore, METTL3 inhibition reduces the expression of several key transcriptional factors for the T-cell effector program and suppresses alloreactive CD4+ T-cell effector function and differentiation. Targeting m6A-related enzymes and molecular machinery in CD4+ T cells represents an attractive therapeutic approach to prevent allograft rejection.

Original languageEnglish (US)
Pages (from-to)718-730
Number of pages13
JournalImmunology and Cell Biology
Issue number9
StatePublished - Oct 2022


  • Allogeneic response
  • METTL3
  • N-methyladenosine
  • STM2457
  • T cells

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Cell Biology


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